A list of all standard mysticism spells can be found on the Spells page. The following individual effects are all considered to be part of the school of Mysticism (see the individual effect pages for full details on availability; the Magical Effects article also provides a summary):

Mysticism is especially handy for thieves. Detect Life is very useful to "see" around corners while Telekinesis can be used to move items out of the owner's sight without having them alert the guards.

Mysticism's Dispel effect can be used to nullify magic (not including powers or enchantments). This applies to both beneficial and malignant magical effects. Using a Dispel spell on one's self when one is afflicted with a negative spell that an enemy used while also under the effects of a beneficial spell casted on the self will dispel both. Although it can be used for both beneficial uses on the self and for nullifying enemy buffs, it is not considered assault when used against nonaggressive NPCs.

Once your renown reaches 50, you can visit the Magnus heaven doomstone to receive the greater power Skein of Magnus. One of several benefits of this power is that it fortifies your mysticism skill 15 points once a day for 120 seconds.